The present disclosure relates to a semiconductor laser drive circuit and a semiconductor laser apparatus.
Recently, an increase in speed of optical communication has been proceeding quickly and Gb/s optical communication systems are put into use. Semiconductor laser diodes such as VCSELs (Vertical Cavity Surface Emitting Lasers) are used as light sources of short wavelength optical transceiver for high speed optical communication systems.
The semiconductor laser diodes are controlled by semiconductor laser drive circuits. With transmission lines, the semiconductor laser diodes are coupled to the semiconductor laser drive circuits because they are manufactured so that each of the semiconductor laser diodes and the associated one of the semiconductor laser drive circuits are made as different semiconductor ICs, respectively.
Impedance matching is achieved between the semiconductor laser diode and its drive circuit in order to carry a driving signal from the drive circuit to the semiconductor laser diode with low power loss and reflection. As mentioned above, the transmission line is used to couple the semiconductor laser diode and its drive circuit together. Therefore, impedance matching between the transmission line and the drive circuit is achieved in order to carry a driving signal from the drive circuit to the semiconductor laser diode with low power loss and reflection.
Among various approaches to impedance matching, for example, there is an approach by providing a terminating resistor for connection to the semiconductor laser drive circuit and there is another approach by providing a damping resistor as disclosed in Japanese Patent Application Laid-open No. 2003-243766.